linux-kernel - Re: [PATCH] sched/topology: Use Identity node only if required

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Message-ID: <20180831120636.GM24124@hirez.programming.kicks-ass.net>
Date:   Fri, 31 Aug 2018 14:06:36 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc:     Ingo Molnar <mingo@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Rik van Riel <riel@...riel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Michael Ellerman <mpe@...erman.id.au>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        Andre Wild <wild@...ux.vnet.ibm.com>,
        Benjamin Herrenschmidt <benh@....ibm.com>
Subject: Re: [PATCH] sched/topology: Use Identity node only if required

On Fri, Aug 31, 2018 at 04:56:18PM +0530, Srikar Dronamraju wrote:
> This was the same in my previous posting too. Before the topology update
> happened, all the cpus would be in SMT, DIE. The topology updates can be
> disabled using a kernel parameter topology_updates=off. Its documented under
> https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html as
> 
>       topology_updates= [KNL, PPC, NUMA] Format: {off} Specify if the kernel
>       should ignore (off) topology updates sent by the hypervisor to this
>       LPAR.
> 
> and is not something new in powerpc.

Doesn't mean it isn't utterly broken.